Heavy-metal pollution has attracted much attention in the public media and scientific community due to the toxic effects of heavy metal ions on human health and the environment. The lead(II) ion, as one of the acutely toxic metal ions, is a dangerous contaminant which causes adverse health effects in humans, including delayed physical and mental developmental in infants and children, kidney disease and high blood pressure in adults. Meanwhile, certain oligonucleotides undergo conformational changes in the presence of particular heavy metal ions.
Atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) are widely-used instrumental techniques for lead(II) ion detection, but their sophisticated instrumentation and/or complicated sample preparation hamper their application for in-field studies. In recent years, fluorescent, colorimetric methods utilizing organic fluorescent dyes, oligonucleotides, or lead(II)-dependent RNA cleaving DNA enzymes have been developed for lead(II) ion detection. A short testing time and portable instrument or tool is required for rapid online detection of lead ions in drinking water around the standard of World Health Organization (WHO) for safe drinking water.